[Tigers] engine ancillaries

[Robert Palmer]

I'll weigh in with my $0.02. It's not really the compression ratio that's
fundamentally related to horsepower, but absolute compression. For example,
I think it's obvious that super/turbo charged motors are more efficient than
ones that are normally aspirated even though they generally run much lower
compression ratios. To the extent that aluminum heads shed more heat, they
can run higher compression ratios to get the same absolute compression at
the same temperature. The comparison test that Sandy cites indicates that
the heat dissipation of aluminum heads is over rated. One thing you can't
argue with - especially in a Tiger - is the appox. 50# weight savings.

-----Original Message-----
From: tigers-bounces+rpalmerbob=roadrunner.com at autox.team.net
[mailto:tigers-bounces+rpalmerbob=roadrunner.com at autox.team.net] On Behalf
Of Stephen Waybright
Sent: Friday, June 13, 2008 6:21 PM
To: tigers at autox.team.net; Sandy Ganz
Subject: Re: [Tigers] engine ancillaries

If Car Craft ran the same compression in both engines, there should be no HP
difference between the iron and alum heads... but the thing is, if all else
is identicle, you can run higher compression with alum heads before the
engine starts pinging because they dissipate heat faster. That's where the
extra HP comes from running Alum heads.